1. FIELD OF THE INVENTION
The present invention relates to a method for producing a high softening point aliphatic petroleum resin. More particularly, it relates to a method for producing an aliphatic petroleum resin which has a high softening point and yet is free from formation of gel and which is industrially useful, by adjusting the composition of the feed oil and by introducing the feed oil to a catalyst.
2. DISCUSSION OF BACKGROUND
The C5 fraction obtained from cracked naphtha or gas oil contains chain conjugated diolefins such as isoprene, 1,3-pentadiene and 1,3-butadiene, or such diolefins plus C.sub.4 -C.sub.10 monoolefinic unsaturated hydrocarbons such as butenes, pentenes and hexenes. However, such C5 fraction also contains cyclopentadiene and dicyclopentadiene which promote formation of a gel and which deteriorates the color of the resin. Such monomer components adversely affecting the resin properties are removed by dimerization and distillation. Then, polymers having various properties are obtained using this fraction as feed material.
There is a polymerization method in which an anhydrous aluminum chloride liquefied catalyst using an oxygen-containing compound or the like as a complexing agent, is used as the polymerization catalyst, and a method in which a solid anhydrous aluminum chloride is used by itself as a catalyst. They are practically employed. The reaction methods using such catalysts are conducted in accordance with a known method such as a batch method or a continuous method, or a method in which the catalyst is introduced into the feed material or a method wherein the feed oil fraction is introduced to the catalyst.